1. Field of the Invention
The present invention relates to shrinkable films and to shrinkable articles prepared therefrom, and more particularly, it relates to films which shrink up to about 50% or more at a low temperature.
More particularly, the present invention relates to a process for producing and articles produced from low-temperature shrinkable film which exhibits a heat shrinkage close to 50% at temperatures ranging from the heat-set temperature to the stretching temperature, said process comprising stretching a polymer film composed of EPDM or EPM, EVA, and talc in a specific ratio more than 1.5 times in at least one direction at a temperature lower than 50.degree. C. and heat-setting the stretched film at a temperature lower than the stretching temperature.
2. Description of the Prior Art
The conventional known process for producing the above-mentioned heat shrinkable film involves the stretching (in one direction or two directions) and winding without heat setting. The conventional heat shrinkable film, therefore, shrinks at a temperature range at which stretching has been accomplished. However, there has been no heat shrinkable film which exhibits a great heat shrinkage at a temperature below 50.degree. C.
For example, polyethylene film stretched at 100.degree.-150.degree. C. begins to shrink at about 120.degree. C. Polypropylene film stretched at about 120.degree. C. begins to shrink at about 130.degree. C. Polyvinyl chloride film stretched at 100.degree.-120.degree. C. begins to shrink at 120.degree. C. Polyvinylidene chloride film stretched at 20.degree.-50.degree. C. begins to shrink at 50.degree.-100.degree. C. The last one is one example which shrinks at low temperatures; but the shrinkage at 50.degree.-60.degree. C. is rather small.
In other words, there has not yet been developed heat-shrinkable film which shrinks more than 50% at a temperature below 50.degree. C.
Heat shrinkable film which exhibits a great shrinkage at low temperatures is expected to find diverse uses as exemplified in the following.
(1) Shrink packaging and sealing of medical and research materials which need low temperature storage or freeze storage (e.g., cap seal of frozen stock tube).
(2) Contact packaging for those products which are not suitable for heating after packaging. Film for contact packaging should conform itself to the size or shape of the object upon heating at a low temperature (e.g., packaging of fresh produce).
(3) Disposable gloves which tightly fit hands upon slight heating of gloved hands. Tight-fitting gloves improve work efficiency.
(4) Protection of gypsum and bandage from wetting and staining, utilizing the ability of shrink film to tightly fit them with ease.
In the field of medical service, gloves are commonly used at the time of blood collecting, operation, and examination. These gloves are required to be disposable for the prevention of infection.
In the field of electronics industry, too, disposable gloves are used for the prevention of environmental pollution.
Disposable gloves are finding more uses in barber shops and beauty parlors and households where cleanliness is required.
For the above-mentioned uses, there are several kinds of disposable gloves, but most of them are on the large side so that they suit many different people. Such gloves are loose and uncomfortable and give the wearer a feeling of physical disorder which decreases work efficiency.
For this reason, there has been a demand for inexpensive, disposable gloves which tightly fit the hands of individuals, without giving the fingers a feeling of physical disorder.
It is a common practice to protect an injured hand or leg with bandage or gypsum, and it is desirable that the bandage or gypsum should be provided with a protective cover when the injured person takes a bath.
It is desirable that those who work in a dusty environment should put protective covers on their hands and legs to keep off dusts. Some machine parts also need protective covers for the same purpose. For safety and hygiene, protective covers which tightly fit the objects are necessary.
Protective covers made of plastics are available in the form of bags in different sizes; but most of them are on the large side so that they suit many different people. Such protective covers are loose and uncomfortable; and they are imperfect to protect bandage or gypsum from wetting and prone to decrease work efficiency.
For this reason, there has been a demand for inexpensive disposable protective covers which tightly fit the objects (such as bandage and gypsum), without giving the wearer a feeling of looseness and physical disorder.
The present invention was completed to solve the above-mentioned problems involved in the prior art technology. Accordingly, it is an object of the present device to provide a heat shrinkable film capable of shrinking as much as 50% at a temperature below about 50.degree. C. Another object of the present invention is to provide inexpensive, disposable gloves which tightly fit the hands of different sizes of individuals, without giving the fingers a feeling of physical disorder and decreasing work efficiency. Another object of the present invention is to provide an inexpensive, disposable, shrinkable protective cover which fits an object and protects it from wetting and dust.